Variable resistor switch



Feb. 27, 1951 l. NESSON VARIABLE RESISTOR SWITCH 2 Sheets-Sheet 1 Filed Nov. 1, 1947 1220922302 Isr aei Wesson, by firm AQ/ v/W flifinflnqyfl Feb. 27, 1951 1. NEssoN 2,543,373

( VARIABLE RESISTOR SWITCH Filed Nov. 1, 1947 2 Sheets-Sheet 2 Fig.8.

13219922303 Icr aeZ Wesson, y fiW W X 721v? @flfawneg s Patented Feb. 27, 1951 VARIABLE RESISTOR SWITCH Israel Nesson, Lynn, Mesa, assignor to Max Zaiger, Swampscott, Mass.

Application November 1, 1947, Serial N 0. 783,580 Claims. (01.201-49) This invention relates to variable resistance controls for electric circuits and pertains more particularly to improvements in resistor switches for controlling low voltage circuits to electric motors, lights or other electrical devices or appliances regulated by a variable resistance.

The principal purpose of the invention is to provide a compact, durable and eflicient variable resistance switch in which the resistor is housed in a sealed chamber or tube containing an inert gas or a substantial vacuum, so that the chamber is substantially free of oxygen and the resistance element is not subject to oxidation which would shorten its life and impair its efficiency, and so that said element does not heat the contacts or other elements of the switch structure which would be adversely affected by proximity of the heated resistor.

Another object is to provide a resistor-containing tube having a plurality of terminals in association with spaced contact plates disposed in the electric circuit and selectively engageable by said terminals, the tube and the contacts being movable with respect to each other for varying the eilective resistance and controlling the now of current in the circuit.

A further object is to provide a sealed tube or chamber containing a filament as well as a resistance element, the filament having a separate terminal engaging a grounded conductor, whereby the tube also serves as a source of illumination at constant brilliancy whenever the circuit is energized.

Additional features and advantages 'of the invention will become apparent from the following description of a recommended embodiment thereof as shown in the accompanying drawings illustrating a resistor switch designed for use in the motor circuit of a heater for motor vehicles or other conveyances. It will be understood, however, that the invention has many other applications in controlling electric circuits for various purposes, and that this invention is not intended to be limited to the field of heater switches or to the structural details of the devices herein illustrated and described, except as defined in the appended claims. In the drawings,

Fig. 1 is a sectional view, partly in elevation, of a variable resistance switch having a sealed, rotatable tube containing a resistor and a light filament;

Fig. 2 is a transverse section taken on line 2-2 of Fig. 1;

Fig. 3 is a bottom view of Fig. 1;

Fig. 4 is a front elevation of Fig. 1 with the I switch base omitted, showing particularly a window opening in the switch housing through which indicia on the rotatable tube casing may be viewed to designate the selected position of the switch:

Fig. 5 is an enlarged elevation of the tube;

Fig. 6 is a bottom view of Fig. 5;

Fig. 'I is a schematic view of the connections between the variable resistance and filament within the tube and the terminals on the base of the tube;

Fig. 8 is a fragmentary developed view of the side of the tube casing, showing the arrangement of the indicia thereon for designating respectively the off, high," fimed. and low positions of the switch; and

Figs. 9 to 12 are diagrammatic views of the relationship of the tube terminals to the contact plates and circuits of the switch, in the four selective positions of the rotatable tube.

In the particular embodimentchosen for the purpose of illustration, the illuminated resistance switch is adapted to be mounted on the instrument panel of an automobile for controlling the 26 speed of the conventional motor for drivingthe heater fan or blower. The base of the switch comprises a pair of insulating discs 2| and 22 fixed to opposite sides of a cup-shaped shell member 23; a pair of resilient contact plates 24 and 25 attached to the upper face of the disc 2| in spaced relation; a metal bracket 26 fastened to the bottom face of the disc 22 and having projecting ends for attaching the base to the instrument panel which affords a ground for the light filament of the switch; a spring arm 21 fixed and grounded to the bracket 26 and engaging a conductor rod 28 passing centrally through the insulating discs; and base terminal parts 29 and 30 fastened to the bottom face of disc 22 by rivets or other fastenings electrically connected to the respective contact plates 24 and 25, said parts being adapted for connection to wires 3| and 32 leading respectively from the car battery 33 or other current source, and to the heater motor 36 or other current-utilizing device (Figs. 9-12). It will be understood that the shell member 23 is suitably apertured to provide passageways for the switch or other fastenings extending through the insulating discs 2| and 22.

A tubular housing 35 of metal or other opaque material, is secured, by screws as in Fig. 1, or otherwise, to the annular flange 36 of shell 23. The upper end of the housing is preferably offset inwardly at flange 31 to provide an annular shoulder 38.

A domed casing 39 of plastic, glass or other translucent 'material, preferably colored to soften illumination from within and prevent glare, is rotatably mounted in the housing 35, the base of the casing having a projecting annular flange 40 engaging under the shoulder 38 of the housing. The inner wall of said flange has a pair of slots 4| extending upwardly from its base; and the inner wall of the casing preferably has an annular groove 42 which reduces the thickness of said wall and permits a greater degree of light transmission in the region immediately within the flange 31 of the opaque housing 35. Said flange has a window opening 43 (Fig. 4) communicating with the thinned wall of the translucent casing. The domed top of the casing may also be formed with segmental surface recesses 44 permitting increased light diffusion at the recessed zones.

The casing receives a removable, sealed tube or chamber 45 having a base shell 46 provided with projecting pins 41 fitting within the casing slots 4 I, whereby the tube may be slid axially into the casing but is restrained from relative rotation therein. The tube accordingly rotates with the casing when the latter is moved by grasping the ridged dome with the fingers. The base of the tube has a sealing and insulating disc 48 carrying a center terminal stud 49 and four arcuately spaced terminal studs 50, 52 and 53. Terminals 5D and 5| are electrically connected by a bridging conductor or shunt 54. Terminal 49 constantly engages the conductor rod 28; the other terminal studs are movable into engagement with the contact plates 24 or 25 as hereafter explained.

The tube proper 45 is made of glass or other suitable transparent material, and is tightly sealed in the base rim 46. The tube contains a resistance wire 55 and a light filament 55. As indicated in Figs. 7 and 9, one end of the resistor 55 is connected by wires or other conductors to the terminal stud 50, and also, through shunt 54, to stud 5|. The center of the resistance wire is connected to terminal stud 52; and the remote end of the resistance is wired to stud 53. The ends of the filament are respectively connected to the terminals 50 and 5|, and to the center stud 43 which is grounded through rod 28, conductor 21 and bracket 25 to the instrument panel, when the switch is installed. The conductor 28 is constantly engaged by the stud 49, so that the filament is illuminated at uniform intensity in any operative position of the switch.

The completed tube is substantially exhausted of air by known methods. The chamber may then be sealed to provide a vacuum tube; or nitrogen, argon or other inert gas may be introduced before the tube is sealed. In either case, the tube is substantially free of oxygen, and the resistance wire as well as the filament are not subject to deterioration by oxidation. The resistor accordingly acts uniformly in aifording resistance of a constant value, and its eflicient life is substantially prolonged. The pilot light filament affords uniform illumination in any operative position of the switch, as will be apparent from Figs. to 12. This light filament is desirable in a heater switch, but it will be evident that it is not essential to the operation of the variable resistance switch, and it may be omitted if desired.

The improved switch is operated by manual rotation of the translucent casing 39 which serves as a switch-knob as well as a, protective and light shield for the tube 45. In the off position, none of the tube terminals are in contact with the plate 24 which is connected to the battery, and no current flows through the filament or resistor (Fig. 9). When the switch is turned to the first or high" position (Fig. 10), terminal 50 engages contact 24, and terminal 5| engages contact 25, so that current flows from battery lead 3| through plate 24 and terminal 5|] to the filament 56, to stud 49, and through conductors 28 and 21 to the grounded bracket 26; and current also flows through shunt 54 to terminal 5| and through plate 25 to the motor lead 32 attached to base terminal 30, without passing through the resistance wire.

In the next or med. position (Fig. 11), terminal 50 continues to engage plate 24, but terminal 5| is located between the contact plates. Current then flows to the filament as aforesaid, and through one-half the resistance wire to terminal 52 and plate 25 engaged thereby, cutting down the effective motor current to medium value.

In the final or low" position (Fig. 12), terminals 5B and 5| are in contact with plate 24, and terminal 52 is in inoperative position between the spaced plates. Current thus fiows to the filament and through all the resistance wire to terminal 53 and plate 25, reducing the effective motor current to a low value.

These four selective positions of the switch are visually indicated to the operator by indicia preferably marked On the casing 33 and visible through the housing window 43 (Fig. 4). The markings may be lettered directly on the tube casing 35 (opposite the groove 42) in opaque ink or paint, as shown in Fig. 8, the respective indicia being spaced according to the degree of rotation required for the four positions of the tube terminals. It is evident that only one complete designation will be observable through the housing window, so that there can be no confusion,

- and no indicia is readily discernible until the tube is lighted. The extinguishment of the light source indicates the off position.

1. A variable resistance switch comprising a sealed chamber substantially free of oxygen, a resistor within the chamber, terminals extending from the chamber, conductors connecting respective terminals with the end portions and with an intermediate portion of the resistor, a shunt conductor connecting one of said respective terminals to another terminal, all of said terminals being disposed in an arc, and a pair of spaced contact members engageable by certain of said terminals and respectively connectable to a current source and to a current-utilizing device, the chamber and said contact members being rotatable relative to each other to complete selective circuits through said shunt conductor thereby by-passing said resistance, through part of said resistance or through substantially all of said resistance.

2. A variable resistance switch comprising a sealed tube substantially free of oxygen and containing a resistance, the bottom of the tube hav ing a plurality of terminals connected to the resistance at the ends thereof and at a point intermediate said ends, respectively, a switch base having a pair of spaced contact members engageable by certain of said terminals, and means operatively connecting the tube and the switch base in relatively rotatable relation, said means comprising slidably engaged elements restraining relative axial movement between said tube and said switch base, whereby said terminals may be moved to selective positions electrically to connect both contact members with part of said resistance or' with substantially all of said resistance.

3. A variable resistance switch comprising a sealed tube substantially free of oxygen and containing a resistance and a light filament, the bottom of the tube having a stud connected to the filament and a plurality of terminals connected to the resistance at the ends thereof and at a point intermediate said ends, respectively, one of said terminals being also connected to said filament, a switch base having a conductor constantly engaged by said stud and a pair of spaced contact members engageable by certain of said terminals, and means operatively connecting the tube and the switch base in relatively rotatable relation, whereby said terminals may be moved A to selective positions electrically to connect both 'the filament and a plurality of terminals connected to the resistance at the ends thereof and at a point intermediate said ends, respectively, one of said terminals being also connected to said filament, a switch base having a conductor constantly engaged by said stud and a pair of spaced pair of spaced contact members engageable by certain of said terminals and respectively connectable to a current source and to a currentutilizing device, the chamber and said contact members being rotatable relative to each other to complete selective circuits through said shunt or through part of said resistance or through substantially all of said resistance, said chamber also containing a light filament and having a center terminal projecting therefrom, the filament being connected to said center terminal and to one of said respective terminals, and said center terminal being connectable to ground, whereby the filament is illuminated to the same degree when any one of said circuits is completed.

'7. A variable resistance switch comprising a sealed tube substantially free of oxygen and concontact members engageable by certain of said,

terminals, and means operatively connecting the tube and the switch base in relatively rotatable relation, whereby said terminals may be moved to selective positions electrically to connect both contact members with part of said resistance or with substantially all of said resistance, the tube also having a terminal stud engageable with said contact members, and a shunt connecting one 7 of said terminals with another of said terminals,

whereby said plates may be directly connected in another selective position of the relatively movable elements.

5. A variable resistance switch comprising a sealed chamber substantially free of oxygen, a resistance wire Within the chamber, terminals extending from the chamber, conductors connecting respective terminals with the end portions and with an intermediate portion of the resistance wire, and a pair of spaced contact members engageable by certain of said terminals and respectively connectable to a current source and to a current-utilizing device, the chamber and said contact members being movable relative to each other to complete. selective circuits through part of said resistance or through substantially all of said resistance, said chamber also containing a light filament and having a center .terminal projecting therefrom, the filament being connected to said center terminal and to one of said respective terminals, and

' said center terminal being connectable to ground,

whereby the filament is illuminated to the same degree when either of said circuits is completed.

6. A variable resistance switch comprising a sealed chamber substantially free" of oxygen, a resistance wire within the chamber, terminals extending from the chamber, conductors connecting respective terminals with the end portions and with an intermediate portion of the resistance wire, a shunt connecting one of said respective terminals to another terminal, all of said terminals being disposed in an arc, and a taining a resistance wire and a light filament, the

bottom of said tube having a terminal stud connectable to ground and a plurality of arcuately disposed terminals, a conductor between the filament and said stud, conductors connecting re spective terminals to the ends of said resistance and to an intermediate part thereof, a shunt connecting one of said respective terminal to another terminalfla housing in which the tube is rotatably mounted, a switch base attached to said housing and having a conductor constantly en- 'gaged by said stud and having a pair of spaced contact plates disposed in position to be engaged by certain of said terminals and respectively connectable to a current source and to a 'currentutilizin device upon rotation of said tube relative to said plates, thereby to complete selective circuits through said shunt or through part of said resistance wire or through substantially all of said resistance wire, the light filament being also connected to one of said terminals and being activated to the same intensity when any one of said circuits is completed.

8. A variable resistance switch comprising a sealed light-transmittin tube substantially free of oxygen and containing a resistance wire and a light filament, the bottom of said tube having a terminal stud connected to the filament and a plurality of terminals connected to said resistance wire at the ends thereof and at a point intermediate said ends, a translucent casing removably receiving the upper portion of said tube in non-rotatable relation, an opaque housing rotatably receiving the base portion of the casing and having an annular flange surrounding the casing, a series of designations on a rotatable member of the switch, said fiange having a window opening through which one of said designations may be viewed, and a witch base attached to said housing and having a conductor engaged by said terminal stud and a pair of spaced contact plates engageable by certain of said terminals upon rotation of said casing, at least one of said terminals being connected to said light filament.

9. A variable resistance switch comprising a sealed light-transmittin tube substantially free of oxygen and containing, a resistance wire and a light filament, the bottom of said tube having a terminal stud connected to the filament and a plurality of terminals connected to said resistance wire at the ends thereof and at a point intermediate said ends, a translucent casing removably receiving the upper portion of said tube in non-rotatable relation, an opaque housing rotatably receiving the base portion of the casing and having an annular flange surroundin the switch base also having means for connecting said conductor to ground and terminal posts for connecting the respective contact plates to a current source and to a current-utilizing device.

10. A variable resistance switch comprising a sealed tube substantially free of oxygen and containing a resistance wire, the bottom of said tube having a plurality of terminals connected to said resistance wire at the ends thereof and at least one point intermediate said ends, a housing in which the tube is rotatably mounted, a switch base attached to said housing and having a pair of spaced contact plates engageable by certain of said terminals and respectively connectable to a current source and a current-utilizing device upon rotation of said tube relative to said housing, thereby to complete selective circuits through part of said resistance wire or through '8 substantially all of said resistance wire, and a bridging conductor connecting two of said terminals and serving to by-pass said resistance wire when said connected terminals engage the respective contact plates.

ISRAEL NESBON.

REFERENCES CITED The following references are of record in the file\of this patent:

UNITED STATES PATENTS Number Name Date 1,809,673 Butler June 9, 1931 1,997,258 Kreizer Apr. 9, 1935 2,043,054 Marty June 2, 1936 2,082,326 Dulberg June 1, 1937 2,195,921 Dulberg Apr. 2, 1940 2,205,288 Hasselbaum June 18, 1940 2,259,792 Batcheller Oct. 21, 1941 2,308,882 Johnson Jan. 19, 1943 2,346,654 Leuthold Apr. 18, 1944 FOREIGN PATENTS Number Country Date 544,494 France Sept. 22, 1922 

